Flotation machine and system utilizing impeller-type aeration units

ABSTRACT

A flotation machine comprising multiple rows of aligned but mutually independent aeration impeller units and respective stators arranged in spaced side-by-side relationship in a straight line substantially normal to the longitudinal across the width of a flotation tank, as well as along the length thereof, for complete independent local pulp circulation, respectively, so there is mutual impingement of the impeller discharges of aerated flotation pulp across the width of the tank, with recirculation of the resulting pulp and consequent unusually effective pulp aeration that might be appropriately termed &#39;&#39;&#39;&#39;superaeration.

O Umted States Patent 1151 3,647,066 Potts et al. 1 Mar. 7, 1972 [54] FLOTATION MACHINE AND SYSTEM 2,628,827 2/1953 Damon ..209/169 X UTILIZING IMPELLER-TYPE afldel'son yers AERATION UNITS 2,892,543 6/ 1959 Damon [72] Inventors: John T. Potts; Lawrence H. Lange; 3,327,851 6/1967 Anderson Thomas P. Liss, all of Salt Lake City, Utah 3,400,818 9/1968 Tar an ..209/ 170 1 Assignee: Gallaher p y Salt Lake y. FOREIGN PATENTS OR APPLICATIONS 471,683 9/1937 Great Britain ..209/ 168 [22] Filed: June 13, 1969 Primary Examiner-Frank W. Lutter [21] Appl' 835296 Assistant Examiner-Ralph J. Hill Remed s Application mm Attorney-David V. Trask and C. Harvey Gold [63] Continuation of Ser. No. 608,339, Jan. I0, 1967, [57 S C abandoned.

r w M A flotation machlne comprismg multiple rows of aligned but 52 us. c1. ..209/169, 261/87, 261/23 R mutually independent mam)" impeller units and respective 51 me c1 ..B03d 1/16 Slam mange! in Spaced side-by'side nImimhip in a [58] Field of Search ..261/87 23 R- 209/168 169 Straight substantially the mgkudinal the g 6 6 width of a flotation tank, as well as along the length thereof, for complete independent local pulp circulation, respectively, f so there is mutual impingement of the impeller discharges of [56] Re erences clsed aerated flotation pulp across the width of the tank, with recir- UNITED STATES PATENTS culation of the resulting pulp and consequent unusually effective pulp aeration that might be appropriately termed su- 1,374,445 4/1921 Greenawalt ..209/ 169 X peraeraflony 1,746,682 2/1930 Ruth ..209/170 2,259,243 10/1941 Damon ..209/169 X 7 Claims, 6 Drawing Figures PATENTEDMAR 7:912 3. 647, 066

SHEET 2 UF 2 26/ INVENTORS JOHN T. POTTS LAWRENCE H LANGE P was BY MALL/NCKRODT 8 MALL/NCKRODT ATTORNEYS THOMAS FLOTATION MACHINE AND SYSTEM UTILIZING IMPELLER-TYPE AERATION UNITS CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of Ser. No. 608,339, filed Jan. 10, l967,now abandoned.

STATE OF THE ART I-Ieretofore, most impeller-type flotation cells have had a single aeration impeller unit, or two or more of such units arranged in a longitudinal series between pulp feed and tailings discharge. The cells have usually been sequentially arranged in a number of relatively short, parallel rows, with distribution of pulp to the individual rows from a main stream of pulp and with reagent addition provided for at a considerable number of locations throughout the system. In those instances where the type of flotation machine utilized has required the forced introduction of air to the aeration impeller unit from a source or sources of compressed air, a complex system of air supply piping has been necessary. Similarly, a complex system of piping or launders has been required for distribution of the feed pulp, regardless of what type of flotation machine has been utilized. Moreover, it has been extremely difficult, if not actually impossible, to maintain equal character of pulp feed to the individual rows of flotation cells.

With the decrease in ore grade encountered in many lowgrade mining properties as mining and milling has continued through the years, and with the current interest in available large deposits of very low grade ores and the growing demand for increased production of metals, there has been a real need for increased flotation mill capacity. Even with high-grade ores, high mill throughout rates are desirable. The trend has been toward employing larger flotation cells, with larger impellers, and to expand the number of rows of cells in a flotation system. This has, however, compounded the problems of mill floor area, pulp distribution, supply of forced air, sampling, reagent addition, and supervisory control, both manual and automatic.

In a known instance where it has been proposed that more than a single row of aeration impeller units be provided across the width of a flotation tank, there is no provision for complete local pulp circulation and the units are staggered in position longitudinally of the tank.

SUMMARY OF THE INVENTION In accordance with the invention, the flotation tank is somewhat wider than normal in any given instance for the purpose of accommodating two or more aeration impeller-stator units across its width, transversely of the length of the cell, so as to provide for lateral circulation of pulp between side-byside impeller units as well as for longitudinal flow from pulp feed box to tailings discharge box. Moreover, instead of distributing the inflowing flotation pulp in parallel to a number of rows of flotation cells, the pulp is fed in full volume to the feed box at the head end of a series of large flotation cells (which are normally arranged in a single long row), utilizing junction boxes in customary manner between series groups of cells whenever this is found desirable and discharging froth into launders paralleling the series and tails into a tailing box at the opposite end of such series.

It is presently seen as most convenient to utilize only two such aeration impeller units side by side, with froth-receiving launders extending along lateral sides of the series longitudinally of the ultimate flow of pulp, but more of the units can be utilized if intermediate launders for froth overflow are provided along the length of the series. Considerably increased pulp aeration is achieved by reason of the fact that the individual impeller and stator combinations are spaced apart to provide for complete localized pump circulation within each combination, but with mutual impingement of impeller discharges of aerated pulp across the width of the flotation tank.

Aeration impeller units that rely on pulling air from the atmosphere are not preferred in this arrangement, but may be used with pulp-circulating types of stator if made to pull a sufficient volume of air to take care of the volume of pulp being handled. Aeration impeller units of forced air type, for example, the type of impeller employed in Agitair" flotation machines manufactured by The Galigher Company, Salt Lake City, Utah, together with the pulp-cirulating type of stator disclosed in the copending patent application of Charles M. Anderson, Ser. No. 427,639, filed Jan. 25, I965 and entitled Flotation Machine and Stator Therefore," now US. Patent No. 3,327,85 l are particularly advantageous. It has been found that a considerably greater quantity of air can be effectively utilized in flotation machines of the invention than has been possible heretofore, with concomitant improved results in pulp aeration.

There is shown in the accompanying drawings a specific embodiment of the flotation system of the invention representing what is presently regarded as the best mode of carrying out the generic concepts in actual practice. From the detailed descrip- DESCRIPTION OF THE DRAWINGS FIG. I represents schematically in plan view a typical prior art system, minus power components and superstructure, which it is intended the system of the invention will replace;

FIG. 2, a similar representation of the system of the invention in a typical preferred form;

FIG. 3, an enlarged fragmentary portion of the system of FIG. 2 taken from the head or feed end and appearing in horizontal section from the standpoint of the line 33 of FIG.

FIG. 4, a transverse vertical section taken on the line 4-4 of FIG. 3 and including the power components and superstructure not shown in FIGS. 2 and 3;

FIG. 5, a fragmentary side elevation of the structure comprehended by the line 5-5 of FIG. 2, and including the power components and superstructure of FIG. 4; and

FIG. 6, a view corresponding to that of FIG. 5 but in longitudinal section taken along the line 6-6 of FIG. 4.

DETAILED DESCRIPTION The particular flotation machine and system illustrated are presented preferred. However, other tank arrangements and other types of aeration impeller and stator combinations can be utilized without departing from the broader inventive concepts.

In the present form, the machine embodies aeration impeller units 10, FIG. 2, of forced air type. Although the system is shown as including junction boxes II between successive longitudinal series groups 12 of individual flotation cells 13, which are defined by partition plates 14 dividing sets of sideby-side aeration impeller units 10 from corresponding succeeding units, the system may taken various forms known to the art. Thus, the partition plates 14 may be eliminated, as may the junction boxes 11, when deemed expedient, depending upon the material being treated and upon other factors of concern to those skilled in the art. Also, only one set, or more than the illustrated two sets, of side-by-side aeration impeller units can be employed in a single cell defined by partition plates I4.

As can be seen from a comparison with the prior art representation of FIG. I, wherein laterally noncommunicating flotation cells IS, each provided with a single aeration impeller unit 16, are arranged back to back in a plurality of parallel rows 17, with a longitudinal wall 18 positively separating flow of pulp in one cell [5 from flow of pulp in the laterally adjoining cell 15. the system of the invention, FIG. 2, differs significantly by providing for lateral flow communication between sidelby-side aeration impeller units, regardless of how many sets of such aligned units are arranged longitudinally in a single cell. There is substantially free intercommunication laterally between such side-by-side aeration impeller units, see FIG. 4, as well as longitudinally from one such sideby-side set of impeller units to the next between pulp feed box I9 and tailings discharge box 20, see FIG. 6, the froth discharging laterally into froth launders 21 which extend longitudinally of the series of cells in customary manner.

Regardless of the particular construction of the aeration impeller unit being utilized in any given installation, provision is made in the impeller-stator combination for complete localized circulation of pulp thereby and for mutual impingement of the respective, side-by-side, local circulations, so as to achieve maximum utilization of impeller air intake. It has been found that, with a forced air type of aeration impeller, such as that provided in the aforementioned Agitair" flotation machine of The Galigher Company, considerably more air can be effectively utilized than is normal. Accordingly, if a type of aeration impeller unit that pulls its own air is utilized, the unit should have adequate air-pulling capacity to take care of the increased quantity of pulp being handled by the system.

In the particular system illustrated, the impeller-stator combinations, see particularly FIGS. 3, 4, and 6, are of the type disclosed in the aforementioned Anderson patent application, Ser. No. 427,639, wherein the aeration impeller unit comprises a disk 10a, fixedly mounted at the lower end of a hollow shaft 100 and having a multiplicity of closely spaced fingers 10b depending from the periphery thereof. The impeller is rotated by an electric motor 22 within a stator 23, which has a plurality of blades 23a mounted on a bottom plate 23b that is supported above the bottom of tank 24 by means of feet 23c.

The individual impeller-stator combinations are spaced apart both laterally and longitudinally, as at 25, to provide complete local circulation for each, even though there is pulp flow intercommunication therebetween.

It is convenient to anchor the feet 230 in a wear pad or plate 26 that covers and protects the bottom of tank 24, and to merely rest the stator bottom plate 23!; thereon. For this purpose, the feet are provided with upstanding pin portions 23d, and the comers of bottom plate 2317 are arcuately indented to accommodate the respective pins and to permit such stator plate to rest on and be supported by the feet. This enables the stators to be easily installed and to be easily removed when desired. For holding the stator firmly in position relative to the impeller during operation and to insure centering during installation, a pair of sets of mating connectors, in the form of a receiving pipe stub 27 depending from the underside of the stator bottom plate 23b and insert pin 28 upstanding from wear pad or plate 26, are provided at diametrically opposite sides of the impeller-receiving openings 29 of the respective stators 23.

Depending upon the character of the flotation pulp being treated, e.g., when the solids are coarse and there is a tendency toward sanding at the bottom of the flotation cell, it is sometimes advantageous to install an upwardly sloping and convergent ridge baffle 30 in the space 25, to positively direct localized circulation of pulp without preventing mutual impingement and intermixing of the discharges of aerated pulp from the individual impeller-stator combinations, and to install generally corresponding baffles 31 and the sidewalls of the tank. It should be realized, however, that the ridge baffle and the side bafiles may or may not be employed, as seen fit in any given instance.

Likewise, it is sometimes advantageous to use froth-crowders, such as shown at 32, FIG. 4, suspended from cross frame members 33 by hangers 32a and extending longitudinally of the tank 24 between the side-by side impeller-stator combinations 10, 23.

The partition plates 14, when utilized, can also be conveniently suspended from cross frame members 33 by hangers 14a, thereby enabling them to be easily removed and replaced as desired.

It has been found that the flow of pulp, with its increased exposure to aeration, permits 5 surprisingly greater rate of pulp feed for any given size flotation system than could be expected from the tank size and from the size and number of aeration impeller units alone. This has advantageous consequences in addition to increased throughput capacity. Thus, by being able to feed more flotation pulp into substantially the same tank space for treatment, the froth given at any given point is loaded with more solid particles than is normal. In other words, a higher than normal tonnage of easily floated particles is subjected to aeration at any given point, thereby producing an unusually heavily loaded froth, which is highly desirable. More air can be used per unit volume of pulp, and more efficient use is made of that air. As a consequence, mill floor space for any given throughput rate is minimized, as are piping and launder requirements for pulp feed. for air feed, (where forced air is utilized), and for froth collection. Moreover, the number of reagent addition and froth sampling points are minimized.

As shown in FIG. 2, the flotation pulp to be treated in the system can be supplied to feed box 19 through a single large conduit 34, instead of through many smaller conduits 35, see FIG. I. Also, the number of supply headers 36, FIGS. 4-6, and distribution pipes 37 for compressed air, when a forced air type of aeration impeller unit is employed, is drastically reduced.

Whereas there is here specifically illustrated and described structure presently contemplated as the best mode of carrying out the invention, it is to be understood that many variations are possible without departing from the inventive subject matter particularly pointed out by the claims that follow.

We claim:

1. A flotation cell comprising:

a tank constructed to maintain a level of flotation pulp therein and including feed means on one side of said tank and discharge means on the opposite side of said tank so that flotation pulp introduced to the tank through said feed means flows substantially longitudinally through the tank and out said discharge means, said tank being open to lateral flow of pulp across its width; and

a pair of aeration impeller units mounted with their impellers in said tank in spaced side-by-side relationship in a straight line substantially normal to the longitudinal direction of pulp flow through the tank such that there is mutual impingement between aerated pulp discharges from said impellers when said aeration impeller units are operating.

2. A flotation cell according to claim I, wherein said aeration impeller units are mounted in said tank with respective stators to comprise respective impeller-stator combinations.

3. A flotation cell according to claim 2, wherein said stators comprise a multiplicity of spaced stator blades radiating from and defining an impeller-receiving space for the reception of a flotation impeller; and a bottom plate supportive of said blades with an opening below said impeller-receiving space, mounted above and approximately parallel the bottom of said tank to provide narrow circulation passages between said bottom plates and the bottom of said tank and said bottom plates and adjacent walls of said tank.

4. A flotation cell according to claim I, including a double row of aeration impeller units, said rows extending approximately parallel the direction of pulp flow with corresponding units in said rows arranged as pairs mounted with their impellers in said tank in spaced side-by-side relationship in lines substantially normal to the direction of pulp flow.

5. A flotation cell according to claim 4,.with two rows of two units each arranged substantially in the form of a square.

6. A flotation cell according to claim 5, wherein said aeration impeller units are mounted in said tank with respective stators to comprise respective impeller-stator combinations.

7. A flotation cell according to claim 6, wherein said stators comprise a multiplicity of spaced stator blades radiating from and defining an impeller-receiving space for the reception of a flotation impeller; and a bottom plate supportive of said blades with an opening below said impeller-receiving space,

mounted above and approximately parallel the bottom of said tank to provide narrow circulation passages between said bottom plates and the bottom of said tank and said bottom plates and adjacent walls of said tank. 5 

1. A flotation cell comprising: a tank constructed to maintain a level of flotation pulp therein and including feed means on one side of said tank and discharge means on the opposite side of said tank so that flotation pulp introduced to the tank through said feed means flows substantially longitudinally through the tank and out said discharge means, said tank being opEn to lateral flow of pulp across its width; and a pair of aeration impeller units mounted with their impellers in said tank in spaced side-by-side relationship in a straight line substantially normal to the longitudinal direction of pulp flow through the tank such that there is mutual impingement between aerated pulp discharges from said impellers when said aeration impeller units are operating.
 2. A flotation cell according to claim 1, wherein said aeration impeller units are mounted in said tank with respective stators to comprise respective impeller-stator combinations.
 3. A flotation cell according to claim 2, wherein said stators comprise a multiplicity of spaced stator blades radiating from and defining an impeller-receiving space for the reception of a flotation impeller; and a bottom plate supportive of said blades with an opening below said impeller-receiving space, mounted above and approximately parallel the bottom of said tank to provide narrow circulation passages between said bottom plates and the bottom of said tank and said bottom plates and adjacent walls of said tank.
 4. A flotation cell according to claim 1, including a double row of aeration impeller units, said rows extending approximately parallel the direction of pulp flow with corresponding units in said rows arranged as pairs mounted with their impellers in said tank in spaced side-by-side relationship in lines substantially normal to the direction of pulp flow.
 5. A flotation cell according to claim 4, with two rows of two units each arranged substantially in the form of a square.
 6. A flotation cell according to claim 5, wherein said aeration impeller units are mounted in said tank with respective stators to comprise respective impeller-stator combinations.
 7. A flotation cell according to claim 6, wherein said stators comprise a multiplicity of spaced stator blades radiating from and defining an impeller-receiving space for the reception of a flotation impeller; and a bottom plate supportive of said blades with an opening below said impeller-receiving space, mounted above and approximately parallel the bottom of said tank to provide narrow circulation passages between said bottom plates and the bottom of said tank and said bottom plates and adjacent walls of said tank. 